.TH relup 4 "sasl 4.3" "Ericsson AB" "Erlang Module Definition"
.SH NAME
relup \- Release upgrade file
.SH DESCRIPTION
.PP
The \fIrelease upgrade file\fR describes how a release is upgraded in a running system.

.PP
This file is automatically generated by \fIsystools:make_relup/3,4\fR, using a release resource file (\fI.rel\fR), application resource files (\fI.app\fR), and application upgrade files (\fI.appup\fR) as input.

.SS "File Syntax"

.PP
In a target system, the release upgrade file is to be located in directory \fI$ROOT/releases/Vsn\fR.

.PP
The \fIrelup\fR file contains one single Erlang term, which defines the instructions used to upgrade the release. The file has the following syntax:

.IP
.nf
{Vsn,
  [{UpFromVsn, Descr, Instructions}, ...],
  [{DownToVsn, Descr, Instructions}, ...]}.

.fi

Vsn = string()
.RS 2
Current release version.


.RE

UpFromVsn = string()
.RS 2
Earlier version of the release to upgrade from.


.RE

Descr = term()
.RS 2
A user-defined parameter passed from the function 
\fIsystools:make_relup/3,4\fR. It is used in the return value of \fIrelease_handler:install_release/1,2\fR.

.RE

Instructions
.RS 2
A list of low-level release upgrade instructions, see 
\fIappup(4)\fR. It consists of the release upgrade instructions from the respective application upgrade files (high-level instructions are translated to low-level instructions), in the same order as in the start script.

.RE

DownToVsn = string()
.RS 2
Earlier version of the release to downgrade to.


.RE

.SS "See Also"

.PP
\fIapp(4)\fR, \fIappup(4)\fR, \fIrel(4)\fR, \fIrelease_handler\fR, \fIsystools\fR